The function of play behavior in the California ground squirrel (Otospermophilus beecheyi) will be investigated. Many hypotheses as to the function of play in animals, including humans, have been proposed. These include practice of adult behaviors, investigation and familiarization with the environment, maintenance of muscle tone in young animals, and socialization of the animal. Little experimental verification of any of these has been attempted. This research will be the first step in examining the hypothesis that play aids in the socialization of the California ground squirrel. It is part of a long-range study designed to investigate the role of play in the establishment of dominance hierarchies, and the role in equipping an animal to interact with unfamiliar conspecifics. This first phase will primarily involve a field study of the behavior of the squirrel, to thoroughly familiarize the investigator with the squirrels' behavior, and to establish a definition of play behavior for the species. Preliminary work with long term deprivation of play in young squirrels will also be done. The squirrels will be required to run on running wheels to receive their food. This will leave little time for play, a low priority behavior. Dominance hierarchies will be determined at this time. After the squirrels have reached sexual maturity, they will be tested in encounters with strange squirrels to determine any effects of the play deprivation on how they interact with strangers. The study should increase our understanding of play behavior in animals, and may give clues as to the function of play in humans. An increase in the general understanding of the development of behavior in an animal's lifetime will also result.